Modern medical treatment often requires medical professionals to introduce fluids into a patient or withdraw fluids from a patient. For example, a patient may need treatment that requires a medical professional to withdraw urine or blood from the urethra or a vein, respectively. Conversely, the medical professional may need to introduce drugs or nutrients into the patient's vein (i.e., intravenously). To create a path for the flow of fluid into or from the patient, one method requires that the medical practitioner use a catheter where one end of the catheter is inserted into the patient. The other end of the catheter connects to an intravenous bag (IV bag), through an IV line. Needleless access connectors employ valves that allow a medical practitioner to remove or add devices (e.g., IV bags) to the catheter without the use of a needle. An example of a needleless access connector is shown in FIGS. 1A and 1B.
FIG. 1A is a cut-away view of a current needleless access connector 100. Needleless access connector 100 includes housing 120, which has female luer fitting 101 at the proximal end, base 130, which has male luer fitting 102 at the distal end, and valve element 103, which sits inside housing 120 and on top of base 130. Housing 120 and base 130 are made from rigid plastic, usually polycarbonate, and the valve element 103 is made from liquid silicone so it is elastic and collapses. When in use, male luer fitting 102 is connected to, e.g., a catheter or to a female luer, and female luer fitting 101 is connected to a fluid reservoir, e.g., an IV bag or male luer. Female luer fitting 101 is connected to the fluid reservoir via a second male luer fitting 106, which has a hollow member (as shown in FIG. 1B) and is inserted through the top of female luer fitting 101. The insertion of male luer 106 collapses valve element 103 down into volume 104 to break the seal and create a fluid flow path. FIG. 1B shows collapsible valve element 103 in the collapsed position after insertion of male luer 106 into female luer 101. Male luer 106 delivers fluid, e.g., from an IV bag, which flows around valve element 103 into channels in male luer fitting 102 and into the catheter or female luer.
Inside valve element 103 is a gap (or septum, not shown), that is filled with air. Needleless access connector 100 is a positive displacement device, so that when a new connection is made at female luer fitting 101, device 100 pulls fluid in from the male side of the valve (i.e., the side proximate male luer fitting 102). When a disconnection is made at female luer fitting 101, device 100 pushes fluid in from the female side (i.e., the side proximate the top of female luer fitting 101). The advantage of positive displacement is that when a disconnection is made, device 100 expels fluid out of the male luer fitting 102 and effectively flushes the catheter. By contrast, some devices on the market today have negative displacement, so that when a male luer (e.g., male luer 106) is disconnected, such devices pull a small amount of liquid from the male luer 102 side. When liquid is pulled from the male luer 102 side of a catheter that is attached to the vein of a patient, blood could be pulled into the catheter lumen and if this blood is left in the catheter lumen it may clot and cause health problems for the patient. Positive displacement connectors avoid this problem by pushing fluid out when a male luer (e.g., male luer 106) is disconnected from the needleless access connector and its collapsible valve moves from its collapsed state to its uncollapsed state. The purging of fluid, from positive displacement connectors, helps to prevent blood from entering the tip of the catheter, thereby preventing blood clotting/contamination and thus, bloodstream infections.
In operation, when the female end of needleless access connector 100 is accessed by a male luer (FIG. 1B), valve element 103 is sufficiently elastic so that it can bend out of the way to allow flow and then return to its original shape after a disconnection is made at the female end. Thus, needleless access connector 100 re-seals itself and forms a flat surface that can be disinfected at the top surface 110 using an alcohol swab.
Before needleless access connector 100 is used to connect a device to, for example, a catheter, needleless access connector 100 will contain some air. This air is removed before using needleless access connector 100 with a catheter because otherwise it may be pumped into the patient causing harm to the patient. Usually, to remove this air, the medical practitioner inverts the needleless access connector and attaches a syringe containing saline to the needleless access connector. The saline is then pushed through the needleless access connector, thereby expelling the air from the connector. (This process is known as priming, and the minimum volume of liquid required to remove all the air from the needleless access connector is known as the priming volume.) Some medical practitioners prefer needleless access connectors with smaller priming volumes to reduce delay in medication delivery.
After a needleless access connector is primed, the medical practitioner usually connects the male end 102 to a catheter (not shown) The medical practitioner connects a male luer from the IV bag (not shown) to the needleless access connector. For example, a medical practitioner would connect the end of syringe 106 to female luer fitting 101, as shown in FIG. 1B.
Of note in needleless access connector 100 is the shapes of housing 120, base 130, and valve element 103. Valve element 103 has flange 105, which is a portion with an outer diameter greater than that of the body of the valve element 103. Housing 120 has shoulder 107, which conforms to flange 105. When assembled, flange 105 is held securely between base 130 and shoulder 107, thereby creating a seal between flange 105 and base 130. The reason for the seal is so that the air in the septum can be vented out without the air getting into the fluid flow path from male luer 106 to male luer 102. Although not shown herein, there are two vent holes in the y-axis direction that extend from the threaded portion of base 130 to the septum of valve element 103 that allow air out of and into the septum as valve element 103 is compressed and uncompressed without mixing with the fluid. Once assembled, housing 120 and base 130 are welded at interface 115.
Flange 105 increases the overall width of valve element 103, and connector 100 allows the fluid to flow around flange 105, thereby making connector 100 itself wide. As a result, connector 100 can look big when compared to a catheter (not shown) and especially when connector 100 is placed against the skin of a neonate. Typical use of connector 100 is to tape the catheter to a patient's skin near the point where the catheter couples to connector 100. However, the wide shape of connector 100 may cause connector 100 to fit uncomfortably against the skin. Additionally, the width of connector 100 can make for a large priming volume.